I. Field of the Invention
This invention relates generally to a machine and method for simultaneously forming threads or fins on multiple elongated cylindrical workpieces.
II. Description of the Prior Art
There are two basic ways of forming integral spiraled threads or fins on a cylindrical workpiece. The first way is to rotate the workpiece and by the use of a cutting tool, cutting away material from the workpiece external surface to leave helical threads or fins formed of the remaining surface material of the workpiece. This system has the basic disadvantage that it is wasteful of material because of the quantity of material that is cut from the workpiece external surface to form the threads or fins. The second basic method and one more preferred particularly for large scale production, is to form threads by rotating thread forming discs against the surface of rotating workpieces in which the workpiece external surface is caused to flow by plastic deformation to form upstanding spiraled threads or fins and in which no material is removed from the workpieces.
Machines for accomplishing the methods of both of these techniques are well known in the industry and are commonly commercially available.
An example of a machine for forming fins or threads on an elongated cylindrical workpiece is illustrated in U.S. Pat. No. 5,003,690, Ray C. Anderson, inventor, issued Apr. 2, 1991. This patent, which is incorporated herein by reference, illustrates and describes a finning and thread rolling machine capable of producing an integral fin tube, an extruded fin tube, a wrap on fin tube or a thread on an elongated cylindrical member. The machine described in this patent forms a spiraled fin or spiraled threads on a single elongated cylindrical workpiece employing a plurality (three illustrated in the patent) of rotating discs that are supported by arbors capable of being adjustably positioned inwardly and outwardly radially from the workpiece. Rotary motion is supplied to the discs to cause the workpiece to also rotate as fins or threads are formed by metal displacement on the exterior of the workpieces.
The system of U.S. Pat. No. 5,003,690 functions very successfully to accomplish its intended result. This patent and the other United States patents cited in this patent is a source of background material relating to the present invention.
The present invention departs from the concept revealed in U.S. Pat. No. 5,003,690 in a basic and dramatic way in that the present invention provides a machine for simultaneously forming threads or fins on a plurality of elongated cylindrical members.